This invention relates to multifilament polyester yarns. More particularly, it relates to an improved multifilament polyester yarn and a new fiber finishing process for polyester yarns in which novel fiber finish compositions are applied to said yarns. Still more particularly, it relates to a fiber finish composition designed specifically for tire cord processing for polyethylene terephthalate yarns.
Many fiber finish compositions are known. Some are quite specific in composition and relate to specific type fibers. Small changes in fiber finish composition frequently result in tremendous improvements in not only processing but also in end use of the fiber.
Polyester tire yarn finishes generally consist of a combination of a lubricant, an antistat, and several emulsifiers. For example, U.S. Pat. No. 3,687,721 discloses an improved polyester tire yarn treated with a composition comprising decaglycerol tetraoleate, glycerol monooleate, ethoxylated tall oil fatty acid, sulfated glycerol trioleate, ethoxylated alkylamine and hexadecyl stearate. Obviously, maintaining the proper ratio of lubricant, antistat and emulsifiers is essential for consistent performance of the tire yarn.
U.S. Pat. No. 2,425,755 discloses novel mixtures of monohydroxy oxyethylene-oxy-1,2-propylene aliphatic monoethers and methods of making such mixtures. This patent states that said mixtures can serve as textile lubricants to give a more desirable "hand" to synthetic fibers; however, the patent does not teach a suitable method for using the products as a spin finish.
U.S. Pat. No. 3,338,830 discloses textile lubricating compositions comprising polyoxyethylated-polyoxpropylated monoethers of exceedingly high molecular weight, e.g., 5,000 or more. This patent teaches that said polyoxyalkylene textile lubricating compositions must contain as essential ingredients a suitable emulsifier and a lubricating ester compound.
Applicants have found that certain polyglycol ethers, particularly mixed polyoxyethylated-polyoxypropylated monoethers, having a relatively low molecular weight of about 300 to 1,000 make the best lubricants when used in a spin finish for the production of polyester tire yarns. Moreover, these polyglycol ethers can be used directly without dilution with water and/or addition of an emulsifier and a lubricating ester compound. Unfortunately, the effectiveness of these lower molecular weight polyglycol ethers as spin finishes is significantly diminished by volatilization loss during high temperature processing of tire yarn. Clearly, it would be a significant advance in this art to find a method to avoid or significantly decrease this volatilization loss.